fix Illegal group reference

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/logging/EasyLogger.java

@@ -4,6 +4,8 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.regex.Matcher;
+
 import org.skywalking.apm.agent.core.conf.Config;
 import org.skywalking.apm.agent.core.conf.Constants;
 import org.skywalking.apm.logging.ILog;
@@ -35,8 +37,10 @@ public class EasyLogger implements ILog {
             if (parametersIndex >= parameters.length) {
                 break;
             }
-
-            tmpMessage = tmpMessage.replaceFirst("\\{\\}", String.valueOf(parameters[parametersIndex++]));
+            /**
+             * @Fix the Illegal group reference issue
+             */
+            tmpMessage = tmpMessage.replaceFirst("\\{\\}", Matcher.quoteReplacement(String.valueOf(parameters[parametersIndex++])));
             startSize = index + 2;
         }
         return tmpMessage;

apm-sniffer/apm-agent-core/src/test/java/org/skywalking/apm/agent/core/logging/EasyLoggerTest.java

@@ -53,6 +53,34 @@ public class EasyLoggerTest {
             .println(anyString());
     }
 
+    @Test
+    public void testLogWithSpecialChar() {
+        PrintStream output = Mockito.mock(PrintStream.class);
+        System.setOut(output);
+        PrintStream err = Mockito.mock(PrintStream.class);
+        System.setErr(err);
+        EasyLogger logger = new EasyLogger(EasyLoggerTest.class);
+
+        Assert.assertTrue(logger.isDebugEnable());
+        Assert.assertTrue(logger.isInfoEnable());
+        Assert.assertTrue(logger.isWarnEnable());
+        Assert.assertTrue(logger.isErrorEnable());
+
+        logger.debug("$$$$");
+        logger.debug("hello {}", "$$$$");
+        logger.info("{}{}");
+        logger.info("hello {}", "{}{}");
+
+        logger.warn("hello {}", "\\");
+        logger.warn("hello \\");
+        logger.error("hello <>..");
+        logger.error("hello ///\\\\", new NullPointerException());
+        logger.error(new NullPointerException(), "hello {}", "&&&**%%");
+
+        Mockito.verify(output, times(9))
+                .println(anyString());
+    }
+
     @Test
     public void testFormat() {
         NullPointerException exception = new NullPointerException();